Control equipment for the headbox tip lath in a paper machine or such and method of tip lath control

ABSTRACT

Control equipment for the headbox tip lath of a paper machine includes first actuators ( 12   a   1   , 12   a   2  . . . ), which are located at different points along the headbox ( 100 ) width and connect functionally with a bendable intermediate part ( 14 ). At the different points along the headbox ( 100 ) width there are also second actuators ( 13   a   1   , 13   a   2  . . . ) which are used in the tip lath control. These connect functionally with both the bendable intermediate part ( 14 ) and the tip lath ( 11 ). The first actuators ( 12   a   1   , 12   a   2  . . . ) are used to perform rough control of the tip lath ( 11 ) whereas the second actuators ( 13   a   1   , 13   a   2  . . . ) are used to perform fine control of the tip lath ( 11 ).

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] This application claims priority on Finnish ApplicationNo.20000495, Filed Mar. 3, 2000, the disclosure of which is incorporatedby reference herein.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

[0002] Not applicable.

BACKGROUND OF THE INVENTION

[0003] The invention concerns control equipment for the headbox tip lathin a paper machine or such and a method for controlling the tip lath.

[0004] Traditionally, controlling of the headbox in Z and CD directionshas been done by using two separate control mechanisms. Controlling overthe whole slice width in the Z direction has been done by opening thetop lip articulated to the frame. On the other hand, profiling in the CDdirection has been done by bending the continuous tip lath by controlspindles located at approximately 100 mm intervals.

[0005] Controlling in the Z direction of the lip slice is mainly neededin grade changes. However, performed research shows that there is nogreat need of control in the Z direction. At dilution headboxes CDcontrol of the slice has mainly been used for zeroing of the lip beforethe start and in some cases for optimising the fibre orientation.

SUMMARY OF THE INVENTION

[0006] The inventive idea is to divide the traditional tip lath controlinto two separate control steps: into fine and rough controlrespectively. Hereby lip zeroing may be done before the start by usingfine control, whereas the rough control may be used for doing asufficient total lip slice control as well as orientation profiling inthe CD direction on a larger scale.

[0007] The solution allows omitting the joint between the top lip andthe top frame, whereby the top lip can be integrated directly into thetop frame. In this way the headbox structure is made considerablysteadier and simpler. In present day headboxes, the lip slice iscontrolled by turning the top lip beam with the aid of worm gearreducers around a joint located at the back edge of the top lip beam.Forces applying to the control spindles of the tip lath and to theirdriving gears become strong due to the large pressure surface area ofthe top lip beam. The internal headbox pressure is directly proportionalto the running speed square, whereby in new high-speed machinesstructures can no longer be made durable or possible structuralsolutions are heavy and expensive. In a two-step tip lath control, wherethe top lip beam of the headbox is fixed, only the pressurised bottomedge of the tip lath will bring about loading of gears and spindles.Hereby the necessary supporting forces also remain small. According topreliminary estimates, considerable savings are achieved in mechanicalmanufacturing costs in the case of a full-width headbox. On the otherhand, strengthening of the framework allows increasing the headboxspeed.

[0008] In the solution, the tip lath is zeroed by such second actuatorsattached to the lath, which may be fine control spindles (with adivision of e.g. about 100 mm). In each control spindle there is an ownindependent spindle length control gear V₁, V₂ . . . The gear may bee.g. an advantageous turnbuckle screw mechanism. Since usually theheadbox lip needs zeroing only once during the useful life of theheadbox, a motor is not necessarily needed in the fine control. All finecontrol spindles are attached directly or by intermediate parts at oneend to an intermediate part extending over the headbox width, preferablyto a beam, which for its part can be moved and bent by rougher firstactuators, that is, by rough control actuators located with a divisionof e.g. 1000 mm CD. The beam is supported in such a way in the framethat it can bend and move in the control direction only. The beam mustbe SO strong that it is able without bending to carry all loads arrivingfrom the tip lath and the fine control spindles. Correspondingly, therough control actuators must be so strong that they can be used forcontrolling the lip slice in the Z direction and for bending the beamextending through the machine in this way to control the fibreorientation in the CD direction.

[0009] Using the solution it is possible to correct an orientationprofile error at a sufficient level using a smaller number of actuatorsand automation cards. With a full-width machine, this means a saving inactuators and automation as well as a considerably speedier control.

[0010] With the proposed solution it is possible to implement a lipslice control that will not change the discharge angle of departure.Thus, the headbox need no longer be tilted to direct the discharge intothe jaw between wires when modifying the lip slice size.Correspondingly, horizontal transfer of the top lip is also eliminated.

[0011] This application thus proposes a two-step tip lath control foruse, whereby two actuators are used, first actuators and secondactuators, which are located functionally after one another in a mutualseries. The first actuators affect a bent intermediate part, forexample, a beam structure, and with the aid of the said first actuatorsrough control of the tip lath is performed and e.g. the fibreorientation profile is affected. The second actuators may simply be finecontrol spindles and they are located with a closer division after thefirst actuators affecting in between the flexible beam and the tip lath,and with the aid of these fine control of the tip lath is performed aswell as e.g. zeroing of the tip lath.

[0012] Thus, as explained above, the headbox according to the inventionmay be used in such an application, where the top lip is notarticulated, whereby no such forces are applied to the tip lath and thegearbox as in an articulated structure turning at its top lip. However,the invention is also suitable for use in such headboxes, where the toplip beam is articulated to turn.

[0013] In state-of-the-art structures, the fibre orientation control isimplemented with the aid of fine control spindles located with anapproximate division of 100 mm. In the structure according to theinvention, the control actuators used for controlling the fibreorientation, that is, the first actuators, are located with a divisionof approximately 1.0 m only. Equipment thus remains small.

[0014] The control equipment for the headbox tip lath in a paper machineor board machine according to the invention and the method for tip lathcontrol are characterised by the features presented in the claims.

[0015] In the following, the invention will be described with referenceto some advantageous embodiments of the invention shown in the figuresof the appended drawings, but the intention is not to limit theinvention to these embodiments only.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1A is a side view of a headbox in a paper machine or boardmachine or such and of a tip lath control equipment according to theinvention located in the headbox.

[0017]FIG. 1B illustrates the structure according to FIG. 1A and thevarious functions of the operation are added in the figure for eachdifferent actuator group.

[0018]FIG. 1C shows in millimeters the magnitude of correction achievedwith the different actuators.

[0019]FIG. 2 illustrates the formation of the first and second actuatorsand their connections with the structures.

[0020]FIG. 3A shows an embodiment of the invention, wherein the secondactuators are mounted into the top front surface of a flexible beam andtheir spindles are mounted through the said beam and are attached to thetip lath.

[0021]FIG. 3B is a sectional view along the line I-I of FIG. 3A.

[0022]FIG. 4A shows an embodiment of the invention, wherein the firstactuators are joined to the top front surface of the flexible beam andalso the second actuators are joined to the top front surface of thesaid flexible beam.

[0023]FIG. 4B is a view of the equipment solution in the direction ofarrow f, of FIG. 4A, that is, from above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024]FIG. 1A shows a side view of a headbox 100 in a paper machine orboard machine or such and of control equipment 10 for the tip lath 11according to the invention. The headbox 100 shown in the figure includesa set of pipes P after a pulp distributing manifold J₁, through whichpipes the pulp flow is conducted to an intermediate chamber E andfurther by way of turbulence generator T into lip cone K and from thelip cone through lip slice A into the jaw between formation wires H₁ andH₂. Lip slice A is controlled by bending tip lath 11 with the aid ofequipment 12 a ₁, 12 a ₂ . . . ; 14; 13 a ₁, 13 a ₂. . . located on thetop surface of top lip beam K₁₀. The top lip beam K₁₀ is fixed andincludes no tilting joint for top lip beam K₁₀. In the equipmentsolution according to the embodiment in FIG. 1A, tip lath 11 is movedaccording to the invention by two functionally series-connectedactuators 12 a ₁, 12 a ₂ . . . and 13 a ₁, 13 a ₂ . . . The firstactuators 12 a ₁, 12 a ₂ . . . are located to connect with a bendableand thus movable intermediate part 14, preferably with a beam extendingover the width of headbox 100, so that the said actuators 12 a ₁, 12 a ₂. . . are located between the intermediate part 14 and stop face R′ ofthe above frame R. With the aid of the said first actuators 12 a ₁, 12 a₂ . . . control of lip slice A is carried out as a rough control, andthe said control is preferably used to perform correction of the fibreorientation profile. The said first actuators 12 a ₁, 12 a ₂ . . . areso-called rough control actuators. Zeroing of the headbox lip and exactcontrol of the tip lath are performed by the second actuators 13 a ₁, 13a ₂ . . . , which are so-called fine control equipment functionallylocated to exert an effect in between the flexible beam 14 and the tiplath 11. The first actuators 12 a ₁, 12 a ₂ . . . are e.g. hydrauliccylinders or spindles moved by motor-gear combinations. The secondactuators 13 a ₁, 13 a ₂ . . . are preferably fine control spindles 15 a₁, 15 a ₂ manually controlled only as regards their length. Generally inthis application, first actuators 12 a ₁, 12 a ₂ . . . are understood asbeing equipment which is used to bring about loading and deformation inthe intermediate part 14 and further through this in the tip lath 11,whereas the second actuators 13 a ₁, 13 a ₂ . . . are understood asbeing such equipment as fine control spindles manually controlled onlyas regards their length, which are located with a closer division andwhich also affect tip lath 11, whereby with the aid of the said secondactuators 13 a ₁, 13 a ₂. . . the tip lath 11 can be controlled and bentinto its desired shape in the fine control stage.

[0025]FIG. 1B illustrates the structure according to FIG. 1A and afunction is added to its presentation, that is, the function broughtabout by each group of actuators 12 a ₁, 12 a ₂ . . . ; 13 a ₁, 13 a ₂ .. .

[0026] The first actuators 12 a ₁, 12 a ₂ . . . are used to affect theflexible beam 14 and give it a certain bent shape, and the beam's bentshape is transferred further to tip lath 11 through the second actuators13 a ₁, 13 a ₂ . . ., which are e.g. fine control spindles 15 a ₁, 15 a₂. The fine control proper is performed by the second actuators 13 a ₁,13 a ₂ . . . , which are located between the concerned intermediate part14, preferably a flexible beam, and tip lath 11.

[0027] The flexible and thus movable intermediate part 14 of the tiplath is a beam extending over the width of the headbox. The secondactuators 13 a ₁, 13 a ₂ . . . are located with a closer division thanthe first actuators 12 a ₁, 12 a ₂ . . . The first actuators and secondactuators 12 a ₁, 12 a ₂ . . . 13 a ₁, 13 a ₂ . . . are functionally ina series in relation to each other.

[0028]FIG. 1C also shows in millimeters the magnitude of the correctionbrought about by the different control equipment when the total controlrange d is ±9 mm. The size of the correction of tip lath 11 which can beperformed by the first actuators 12 a, 12 a ₂ . . . is ±8 mm, while thesize of the correction of tip lath 11 which can be performed by thesecond actuators 13 a ₁, 13 a ₂ . . . is ±1 mm.

[0029]FIG. 1C illustrates an embodiment for forming the actuators 12 a₁, 12 a ₂ . . . and 13 a ₁, 13 a ₂ . . . As is illustrated in FIG. 2,the first actuators 12 a ₁, 12 a ₂ . . . are so calledmotor-gear-spindle combinations M₁, V₁, 16 a ₁, which connect in betweenthe front face R′ of frame R and the flexible and thus movableintermediate part 14, preferably a beam. Motor M₁, M₂ . . . may be anelectric motor. As further illustrated in FIG. 2, located in between tiplath 11 and the beam of flexible intermediate part 14 there are secondactuators 13 a ₁, 13 a ₂ . . . , so-called fine control actuators, whichin the embodiment illustrated in FIG. 2 are formed by spindles 15 a ₁′,15 a ₁′, which at their end threads are joined functionally to oneanother through a connecting internally threaded bushing 17 a ₁. Byturning bushing 17 a ₁ tip lath 111 is affected between the ends ofspindles 15 a ₁′, 15 a ₁″ by changing the combined length. At its oneend spindle 15 a ₁″ is connected with beam 14, and spindle 15 a ₁′ isconnected at its one end with tip lath 11. When fine control of tip lath11 is performed by the second actuators 13 a ₁, 13 a ₂ . . . , beam 14hereby remains in the standard position and only tip lath 11 is bent.The first actuators 12 a ₁, 12 a ₂ . . . hereby keep beam 14 in acertain exact position.

[0030] For example, in fibre orientation control beam 14 is bent by thefirst actuators 12 a ₁, 12 a ₂ . . . and the bent shape given to thebeam is passed on through the spindles 15 a ₁, 15 a ₂. . . of the secondactuators 13 a ₁, 13 a ₂ . . . of tip lath 11 or through similar parts.Thus, tip lath 11 can be controlled as desired by bending it along itsentire length.

[0031] In FIG. 2 the distance between the first actuators 12 a ₁, 12 a₂. . . is S₁, and the distance between the second actuators 13 a ₁, 13 a₂ is S₂. S₁>S₂, that is, the first actuators 12 a ₁, 12 a ₂ . . . arelocated with a less close division than the second actuators 13 a ₁, 13a ₂ . . . Under these circumstances, the second actuators 13 a, 13 a ₂ .. . are located with a closer division than the first actuators 12 a ₁,12 a ₂ . . . In the embodiment shown in the figure, the top lip beam K₁₀is fixed and does not include any tilting joint for the top lip beamK_(10.)

[0032]FIG. 3A shows an embodiment of the invention, wherein the secondactuators 13 a ₁, 13 a ₂ . . . are mounted on to the top front face ofintermediate part 14, preferably a bendable beam. Each actuator 13 a ₁,13 a ₂ . . . can be used to affect a separate fine control spindle 15 a₁, 15 a ₂ . . . and further to affect tip lath 11. The fine controlspindles 15 a ₁, 15 a ₂ . . . are located through beam 14 and further attheir one end to connect with tip lath 11. The first actuators 12 a ₁,12 a ₂ . . . are also located to connect with the bendable intermediatepart 14, preferably a beam, in between stop face R′ and intermediatepart 14.

[0033]FIG. 3B shows a sectional view along line I-I of FIG. 3A.

[0034]FIG. 4A shows an embodiment of the invention, wherein the stopface R′ of the first actuators 12 a ₁, 12 a ₂ . . . is located below thefirst and second actuators 12 a ₁, 12 a ₂ . . . ; 13 a ₁, 13 a ₂ . . .The first actuators 12 a ₁, 12 a ₂ . . . affect between the said stopface R′ and the flexible intermediate part 14, preferably a beamextending across the width of the headbox, and correspondingly thesecond actuators 13 a ₁, 13 a ₂ . . . affect between the saidintermediate part 14 and tip lath 11. In the embodiment, the secondactuators 13 a ₁, 13 a ₂ . . . connect with the top front face of theintermediate part 14, preferably a beam, as do the first actuators 12 a,12 a ₂ . . . The spindles of the first actuators 12 a ₁, 12 a ₂ . . .are located through beam 14 to be attached to stop face R′. Likewise,the spindles of the second actuators 13 a ₁, 13 a ₂ . . . are locatedthrough beam 14 to be attached to tip lath 11.

[0035]FIG. 4B is a view from above of a structure in the direction ofarrow f₁ of FIG. 4A.

[0036] It is understood that the invention is not limited to theparticular construction and arrangement of parts herein illustrated anddescribed, but embraces such modified forms thereof as come within thescope of the following claims.

We claim:
 1. Control equipment for a headbox tip lath of a papermachine, comprising: a plurality of first actuators, which are locatedover a width of a headbox and which connect functionally with a bendableintermediate part; and a plurality of second actuators, which are usedfor controlling the tip lath over the headbox width and which connectfunctionally with the bendable intermediate part and with the tip lath,and that with the aid of the first actuators rough control of the tiplath is carried out and with the aid of the said second actuators finecontrol of the tip lath is carried out.
 2. The control equipment for aheadbox tip lath of a paper machine of claim 1 wherein the bendableintermediate part is a beam which extends over the width of the headbox,and wherein the first actuators are spaced a first distance apart in across machine direction, and the second actuators are spaced a seconddistance apart in the cross machine direction, the second distance beingless than the first distance.
 3. The control equipment for a headbox tiplath of a paper machine of claim 1 wherein the second actuators comprisefine control spindles, the length of which can be controlled.
 4. Thecontrol equipment for a headbox tip lath of a paper machine of claim 1wherein the first actuators are located between a fixed stop face andthe bendable intermediate part, and wherein the second actuators arelocated between and connected to both the intermediate part and the tiplath.
 5. The control equipment for a headbox tip lath of a paper machineof claim 1 wherein each of the first actuators comprises an electricmotor which through a gear moves a spindle which is connected to theintermediate part.
 6. The control equipment for a headbox tip lath of apaper machine of claim 5 wherein each first actuator spindle is joinedthrough a gearbox and motor to a fixed stop face of the frame.
 7. Thecontrol equipment for a headbox tip lath of a paper machine of claim 1wherein the first and second actuators are located on a top surface of atop lip beam of a lip cone of a headbox in the paper machine.
 8. Thecontrol equipment for a headbox tip lath of a paper machine of claim 1wherein the bendable intermediate part has a top front face, and whereinthe second actuators are mounted to the front face such that portions ofthe second actuators extend through the bendable intermediate part to beconnected to the tip lath.
 9. The control equipment for a headbox tiplath of a paper machine of claim 1 wherein the first actuators areconnected with the bendable intermediate part and with a stop face whichis located in between the intermediate part and the tip lath and belowthe intermediate part.
 10. The control equipment for a headbox tip lathof a paper machine of claim 1 wherein the control equipment forms a partof a headbox including a slice having a fixed top lip beam, and whereinthe control mechanism is fixed to the headbox, the top lip beam havingno joint for opening a lip cone.
 11. A method for controlling a tip lathof a headbox in a paper machine, the headbox having a plurality of firstactuators spaced in the cross machine direction over a width, the firstactuators extending between a stop face, and a bendable intermediatepart, and have a plurality of second actuators spaced int the crossmachine direction over the width, the second actuators extending betweenthe bendable intermediate part and the tip lath, comprising the stepsof: actuating the first actuators to perform rough control of the tiplath; and actuating the second actuators to perform fine control of thetip lath.
 12. The method of claim 11 wherein the second actuatorscomprise fine control spindles connected to the tip lath, and whereinthe acuating of the first actuators affects the bendable intermediatepart which extends over the headbox width, in such a way that the bentshape is transferred further from the intermediate part through thesecond actuators to the tip lath, and that the fine control proper ofthe tip lath is performed by the second actuators.
 13. A paper machineheadbox, comprising: a slice extending in a cross machine direction afirst width, the slice having a top lip beam; a frame fixed with respectto the top lip beam and extending the first width; a plurality of firstactuators mounted to the frame and spaced from one another in the crossmachine direction, a bendable intermediate beam to which each firstactuator is connected; a plurality of second actuators, connected to theintermediate beam, and a tip lath extending the first width, wherein thesecond actuators extend between the intermediate beam and the tip lath,the first actuators being adjustable for rough control of the tip lath,and the second actuators being adjustable for fine control of the tiplath.
 14. The paper machine headbox claim 13 wherein the bendableintermediate beam extends over the width of the headbox, and wherein thefirst actuators are spaced a first distance apart in a cross machinedireciton, and the second actuators are spaced a second distance apartin the cross machine direction, the second distance being less than thefirst distance.
 15. The paper machine headbox of claim 13 wherein thesecond actuators comprise fine control spindles, the length of which canbe controlled.
 16. The paper machine headbox of claim 13 wherein thefirst actuators are located between a stop face fixed to the frame andthe bendable intermediate beam, and wherein the second actuators arelocated between and connected to both the intermediate bendable beam andthe tip lath.
 17. The paper machine headbox of claim 13 wherein each ofthe first actuators comprises an electric motor which through a gearmoves a spindle which is connected to the intermediate part.
 18. Thepaper machine headbox of claim 17 wherein each first actuator spindle isjoined through a gearbox and motor to the fixed stop face of the frame.19. The paper machine headbox of claim 13 wherein the bendableintermediate part has a top front face, and wherein the second actuatorsare mounted to the front face such that portions of the second actuatorsextend through the bendable intermediate part to be connected to the tiplath.
 20. The paper machine headbox of claim 13 wherein the firstactuators are connected with the bendable intermediate part and with astop face connected to the frame and which is located in between theintermediate beam and the tip lath and below the intermediate beam.